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respiratory system year 1 > pathology of respiratory tract infection > Flashcards

pathology of respiratory tract infection Flashcards

1
Q

what 3 factors affect lung infections

A

microorganism pathogenicity
capacity to resist infection
population at risk

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2
Q

microorganism pathogenicity (3)

A

primary - very infective and dangerous
facultative - need help to spread e.g. immunosuppression
opportunistic - generally wouldnt be able to cause infection in a healthy person, require significant reduction in defence mechanisms

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3
Q

capacity to resist infection (2)

A

state of host defence mechanisms

age of patient

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4
Q

population at risk

A

exposure is necessary to be able to contract the disease
environment - susceptible to host breeding
living conditions and the ability of the pathogen to spread

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5
Q

6 type of URTI

A 
coryza - common cold 
sore throat syndrome
acute laryngotracheobronchitis (croup) 
laryngitis
sinusitis
acute epiglottitis
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6
Q

what organism causes the majority of URTI

A

viral infection

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7
Q

acute epiglottitis causative organism

A 
haemopholius influenzae (type B - Hib)
group A beta haemolytic streptococci - complete haemolysis 
rarely cause by parainfluenza virus type 4 but other viruses may be responsible
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8
Q

what does acute epiglottitis cause

A

dramatic swelling of the epiglottis
can obstruct the airway
can be fatal in paediatrics but is treatable

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9
Q

3 type of LRTI

A

bronchitis
bronchiolitis
pneumonia

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10
Q

is bronchiectasis an infection

A

NO
widening of the airways
build up of XS mucus
prone to infection

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11
Q

what is bronchitis

A

inflammation of the bronchus

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12
Q

what is bronchiolitis

A

bronchiole inflammation

caused by RSV (respiratory syncytial virus)

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13
Q

what part of the lung does pneumonia involve

A

infection involving the conducting part of the lung (alveolar airspace)

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14
Q

4 types of respiratory tract defence mechanisms

A

MACROPHAGE MICOCILIARY ESCALATOR
general immune system (humoral and cellular)
respiratory tract secretions
URT as a filter

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15
Q

role of upper respiratory tract as a filter

A

nasal hair acts as a filter
turbulent airflow
lined with mucus to trap material

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16
Q

role of respiratory secretions in preventing infection - problems

A

XS of secretions e.g. mucus in CF, pulmonary oedema in cardia failure
accumulation of secretions leads to increased chance of infection - acts as a culture medium and organisms can escape the defence mechanisms

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17
Q

3 components of the macrophage mucociliary escalator

A

alveolar macrophages
mucociliary escalator
cough reflex

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18
Q

role of alveolar macrophages

A

phagocytic

remove material that has reached the alveolar airspace

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19
Q

role of mucociliary escalator

A

system of moving mucus from the lower lungs up into the throat

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20
Q

role of the cough reflex

A

kicks in to help us expel what has been removed from the lungs or we swallow it

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21
Q

is the normal LRT sterile?

A

YES

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22
Q

what are two important factors that affect the health of the MC escalator

A

temperature

humidity

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23
Q

viral infection and the MC escalator

A

viral infections can lead to damage to the MC escalator
e.g. influenza infection: cells are targeted, cytopathic effect, in severe infection the normal ciliated epithelium is replaced by useless virus infected cells, higher risk of 2y bacterial infection

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24
Q

effect of bronchiolitis

A

bronchioles are usually the target of viral infection
inflammation
inflammatory exudate which accumulates in the airways and can cause respiratory distress

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25
Q

classification of pneumonia (3)

A

anatomical - what part of the lung is affected
aetiological - circumstances under which the infection occurred
microbiological -appropriate for treatment

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26
Q

aetiological classification of pneumonia

A

community acquired
hospital acquired (nosocomial)
in the immunocompromised
atypical - unusual organisms
aspiration - substances that should have gone down digestive tract
recurrent - consider how patient’s defence mechanisms are failing

27
Q

patterns of pneumonia

A

bronchopnuemonia, segmental, lobar - important for anatomical pneumonia (how much of the lung is infected and where)

hypostatic - lots of lung secretions are accumulating, aspiration, obstructive + retention (both related to cancer), endogenous lipid

28
Q

bronchopneumonia

A

affects bronchioles and alveoli surrounding the bronchioles
acute inflammation - neutrophil polymorphs may be seen in sputum sample
focal process - localised infection in the small airways and nearby alveolated lung tissue
often doesnt reach the pleura

usually have another disease which leads to bronchopneumonia e.g. COPD - facultative pathogens

29
Q

bronchopneumonia on CXR

A

often bilateral basal patchy opacification

focal nature of consolidation

30
Q

lobar pneumonia

A

seen from 1y pathogens in young, healthy people

vigorous inflammtory response and inflammation fills the entire lung/lobe until they can spread out further

31
Q

outcome/complications of pneumonia

A 
MOST RESOLVE 
pleurisy, pleural effusion ,empyema - pus accumulates in pleural space
organisation
lung abscess
bronchiectasis 
potentially fatal
32
Q

organisation as an outcome of pneumonia

A

mass lesion - less common, scar/fibrous tissue, often confused with cancer
COP (cryptogenic organising pneumonia - BOOP)
constrictive bronchiolitis

33
Q

conditions where lung abscesses are more likely to develop

A

obstructed bronchus (tumour)
aspiration
S. aureus, some pneumococci, Klebsiella

very rare: metastatic in pyaemia, necrotic lung (2y infection)

34
Q

lung abscess

A

can be fatal
infection is present as well as destruction and necrosis of the infected tissue - space develops where pus can accumulate

35
Q

bronchiectasis is the pathological dilation of bronchi due to: (4)

A

severe infective episode
recurrent infections
proximal bronchial obstruction
lung parenchymal destruction

36
Q

clinical symptoms of bronchiectasis

A 
75% start in childhood
COUGH, ABUNDANT PURULENT FOUL SPUTUM
haemoptysis
signs of chronic infection
coarse crackles
clubbing
37
Q

infections and treatment of bronchiectasis

A

thin section CT
postural drainage
Abx
surgery - resect affected area f lung

38
Q

complications of bronchiectasis

A

acute/chronic suppuration

haemorrhage - severe risk in bronchiectasis, can be fatal

39
Q

recurrent lung infection

A

local bronchial obstruction - tumour, foreign body
local pulmonary damage - bronchiectasis
generalised lung disease - CF, COPD
non-respiratory disease, HIV/other, aspiration

40
Q

aspiration pneumonia

A 
vomiting 
oesophageal lesion
obstetric anaesthesia
neuromuscular disorders
sedation
41
Q

where does aspirated material tend to end up

A

right main bronchus

apical segment of right lower lobe

42
Q

opportunistic infections

A

increased change of ‘ordinary infections’

caused by opportunistic pathogens

43
Q

opportunistic pathogens

A

not normally capable of producing disease in patients with intact lung defences

low grade bacterial pathogens
CMV
pneumocystitis jirovecii
other fungi and yeasts

44
Q

normal air flow in airways

A

bulk flow - laminar (trachea and main bronchi, bronchioles), turbulent (nose)
depends on pressure difference

45
Q

what causes the blood air barrier

A

alveolar lung tissue

46
Q

why is Hb 98% saturated at FIO2 21%

A

affinity for oxygen

47
Q

solubility of CO2

A

very soluble

rapidly equilibrates between blood and air

48
Q

normal PaO2

A

10.5-13.5kPa

49
Q

normal PaCO2

A

4.8-6.0kPa

50
Q

type I respiratory failure

A

PaO2 <8kPa
PaCO2 normal or low
fall in [O2] in peripheral arterial blood
generally occurs as a result of gas exchange failure in part or all of lungs

51
Q

type II respiratory failure

A

PaCO2 >6.5kPa
PaO2 usually low
failure to get rid of CO2
failure in ventilation

52
Q

4 abnormal states associated with hypoxaemia

A

ventilation/perfusion imbalance
diffusion impairment
alveolar hypoventilation
shunt

53
Q

pulmonary vascular changes in hypoxia

A

physiological pulmonary arteriolar vasoconstriction

it is a protective mechanism to avoid sending blood to alveoli short of oxygen

54
Q

physiological pulmonary arteriolar vasoconstricton

A

occurs when alveolar oxygen tension falls
can be localised effect
ALL VESSELS CONSTRICT if there is arterial hypoxaemia i.e. global lung disease

55
Q

why does hypoxaemia occur in pnuemonia

A

V/Q mismatch - bronchitis/bronchopnuemonia (some ventilation of abnormal alveoli but not enough)
shunt - severe bronchopneumonia, lobar pattern with large areas of consolidation (large amount of lung isn’t engaging in any gas exchange but is still being perfused)

56
Q

V/Q mismatch

A

low V/Q is commonest cause of hypoxaemia
low V/Q in some alveoli arises due to local alveolar hypoventilation due to some, focal disease
hypoxaemia due to low V/Q responds well to small increases of FIO2

57
Q

define shunt

A

blood passing from R to L side of heart without contacting ventilated alveoli
normally 2-4% shunt

58
Q

when does pathological shunt occur

A

AV malformations
congenital heart disease
pulmonary disease

59
Q

how do large shunts respond to increase in FIO2

A

they respond poorly

blood leaving NORMAL lung is already 98% saturated

60
Q

why does hypoxamia occur in COPD (4)

A

airway obstruction
reduced respiratory drive
loss of alveolar SA
only during acute exacerbation

61
Q

alveolar hypoventilation

A

insufficient amount of air moved in and out of lungs
increased PACO2, increased PaCO2
decreased PAO2, decreased PaO2
fall in PaO2 due to hypoventilation is corrected by raising FIO2

62
Q

why does pulmonary hypertension occur in hypoxic cor pulmonale (5)

A 
PULMONARY VASOCONSTRICTION
pulmonary arterioles (muscle hypertrophy and intimal fibrosis)
loss of capillary bed
2y polycythaemia (high [RBC] in blood)
bronchopulmonary arterial anastamoses
63
Q

define chronic (hypoxic) cor pulmonale

A

hypertrophy of the RV resulting from disease affecting the function and/or structure of the lung

except where pulmonary alterations are the result of diseases primarily affecting the L side of the heart or congenital heart disease

respiratory system year 1 (25 decks)

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